As part of the Data Invulnerability Architecture (DIA), all the files on a Data Domain Restorer (DDR) are verified to ensure completeness. Verification includes reading all indirect segments in a segment tree and ensuring existence of leaf segments in the segment tree for a file. If, during verification, any missing segments are discovered, an alert is generated to identify the files with missing segments. The primary motivation for verifying the files is to identify data loss due to software errors during ingest, replication, or garbage collection (GC).
Verification can be performed inline during ingest. Upon new segment arrival, segment reachability checks can be performed for the new segments when they are being written. However, if a bug causes a missing segment, that segment would be missed. The advantage of performing file verification offline, as opposed to inline, is that there is a background job which checks for reachability in case a software bug in write path, GC or replication caused a missing segment.
Data Domain systems, such as the DDR, are designed to ensure reliable recovery of data. The DDR DIA architecture provides inline write and read verification, which protects against and automatically recovers from data integrity issues during data ingest and retrieval. Capturing and correcting input/output (I/O) errors inline during the backup process eliminates the need to repeat backup jobs, ensuring that backups complete on time and satisfy service-level agreements. In addition, unlike other enterprise arrays or file systems, continuous fault detection and self-healing ensures data remains recoverable throughout its lifecycle on the DDR.